Foam Stops should only be used by a trained medical professional, audiologist or hearing aid dispenser.Foam Stops must be compressed to fit and properly block the ear canal. DO NOT use a size that is the same diameter as or smaller than the ear canal. The user of Foam Stops is also cautioned against the use of this product in taking an ear impression of a patient with a perforated or missing eardrum or other abnormality of the outer or middle ear.